/*
 * Copyright (C) 2007 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.collect;

import com.google.common.annotations.GwtCompatible;
import com.google.errorprone.annotations.CanIgnoreReturnValue;

import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import javax.annotation.CheckForNull;

import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Basic implementation of the {@link ListMultimap} interface. It's a wrapper around {@link
 * AbstractMapBasedMultimap} that converts the returned collections into {@code Lists}. The {@link
 * #createCollection} method must return a {@code List}.
 *
 * @author Jared Levy
 * @since 2.0
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
abstract class AbstractListMultimap<K extends @Nullable Object, V extends @Nullable Object>
        extends AbstractMapBasedMultimap<K, V> implements ListMultimap<K, V>
{
    /**
     * Creates a new multimap that uses the provided map.
     *
     * @param map place to store the mapping from each key to its corresponding values
     */
    protected AbstractListMultimap(Map<K, Collection<V>> map)
    {
        super(map);
    }

    @Override
    abstract List<V> createCollection();

    @Override
    List<V> createUnmodifiableEmptyCollection()
    {
        return Collections.emptyList();
    }

    @Override
    <E extends @Nullable Object> Collection<E> unmodifiableCollectionSubclass(
            Collection<E> collection)
    {
        return Collections.unmodifiableList((List<E>) collection);
    }

    @Override
    Collection<V> wrapCollection(@ParametricNullness K key, Collection<V> collection)
    {
        return wrapList(key, (List<V>) collection, null);
    }

    // Following Javadoc copied from ListMultimap.

    /**
     * {@inheritDoc}
     *
     * <p>Because the values for a given key may have duplicates and follow the insertion ordering,
     * this method returns a {@link List}, instead of the {@link Collection} specified in the {@link
     * Multimap} interface.
     */
    @Override
    public List<V> get(@ParametricNullness K key)
    {
        return (List<V>) super.get(key);
    }

    /**
     * {@inheritDoc}
     *
     * <p>Because the values for a given key may have duplicates and follow the insertion ordering,
     * this method returns a {@link List}, instead of the {@link Collection} specified in the {@link
     * Multimap} interface.
     */
    @CanIgnoreReturnValue
    @Override
    public List<V> removeAll(@CheckForNull Object key)
    {
        return (List<V>) super.removeAll(key);
    }

    /**
     * {@inheritDoc}
     *
     * <p>Because the values for a given key may have duplicates and follow the insertion ordering,
     * this method returns a {@link List}, instead of the {@link Collection} specified in the {@link
     * Multimap} interface.
     */
    @CanIgnoreReturnValue
    @Override
    public List<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values)
    {
        return (List<V>) super.replaceValues(key, values);
    }

    /**
     * Stores a key-value pair in the multimap.
     *
     * @param key   key to store in the multimap
     * @param value value to store in the multimap
     * @return {@code true} always
     */
    @CanIgnoreReturnValue
    @Override
    public boolean put(@ParametricNullness K key, @ParametricNullness V value)
    {
        return super.put(key, value);
    }

    /**
     * {@inheritDoc}
     *
     * <p>Though the method signature doesn't say so explicitly, the returned map has {@link List}
     * values.
     */
    @Override
    public Map<K, Collection<V>> asMap()
    {
        return super.asMap();
    }

    /**
     * Compares the specified object to this multimap for equality.
     *
     * <p>Two {@code ListMultimap} instances are equal if, for each key, they contain the same values
     * in the same order. If the value orderings disagree, the multimaps will not be considered equal.
     */
    @Override
    public boolean equals(@CheckForNull Object object)
    {
        return super.equals(object);
    }

    private static final long serialVersionUID = 6588350623831699109L;
}
